Giffords, who was wounded in a mass shooting a little more than two years ago, and her husband Mark Kelly have become the two of the most prominent pro-gun control voices after Newtown. The couple will be on hand for the speech thanks to Rep. Ron Barber (D-AZ) — Giffords’ former staffer who replaced her after she resigned — and Sen. John McCain (R-AZ).

Kelly and Giffords recently launched a super PAC aimed at supporting pro-gun control politicians. Groups like theirs and one founded by New York City Mayor Mike Bloomberg are helping change the game on gun control, giving proponents the resources they never had to take on the NRA. To that end, Kelly and Giffords will host a big fundraiser for their PAC before the president’s address “at one of Ms. Giffords’s favorite restaurants” in Washington, the New York Times reported over the weekend.

Ms. Giffords and Mr. Kelly are particularly focused on two areas that Mr. Obama is pushing: an enhanced system of background checks that would prevent more criminals and the mentally ill from buying guns, and a limit on the capacity of magazines.

“A universal background check would have directly affected what happened here in Tucson,” Mr. Kelly said, referring to the shooting in which six people were killed and many others, including his wife, were injured. The gunman, Jared L. Loughner, had been suspended from community college for behavioral reasons.

Ms. Giffords’s two organizations have already raised millions of dollars from small online donations and from bigger gifts, including $1 million from Steve and Amber Mostyn, Houston trial lawyers, and a six-figure donation from Mr. Bloomberg. The political action committee will hold a fund-raiser before the State of the Union address on Tuesday night in Washington at one of Ms. Giffords’s favorite restaurants.